As indicated in the September 1996 issue of xe2x80x9cGolf Digestxe2x80x9d, hitting golf balls into the water occurs with a great degree of frequency. As a result, an entire industry has developed in the recovery of golf balls which are then resold despite the fact that the ball has spent a fair amount of time in the water. While the golf ball cover seems to be fairly impervious, the question has become as to the effect of the immersion of the ball over a number of days at the bottom of a pond laying in the mud.
As will be appreciated, golf balls come in two varieties, a three-piece ball and a two-piece ball. According to the above article, when such balls were tested using a robotic hitting machine and a standard length metal driver with a 9.53 degree loft and an extra stiff shaft, with a club head speed 93.7 miles per hour and a launch angle of 9.0 degrees and with a spin rate of 2,800 rpm, the result for a three-piece ball was a difference in carry of 6 yards after an eight day immersion, a 12 yard loss after three months and a 15 yard loss after six months.
For a two-piece ball, the amount of carry was 6 yards shorter and after having been immersed for eight days was a total of 9.1 yards shorter. While for two-piece balls being in the water typically makes the ball harder in terms of compression, it also shows down the coefficient of restitution or the ability of the ball to regain its roundness after impact. The above factors make the ball fly shorter. Three-piece balls have been found to get softer in terms of compression, but they also fly shorter according to the above-mentioned article.
Whatever the results of the immersion of a golf ball in a pond, the characteristics of the ball in flight are altered by the immersion. The problem therefore becomes one of being able to determine when a golf ball has been immersed so that it may be rejected in favor of a new golf ball.
Note that golf ball construction is shown in the following U.S. Pat. Nos. 5,609,953; 5,586,950; 5,538,794; 5,496,035; 5,480,155; 5,415,937; 5,314,187; 5,096,201; 5,006,297; 5,002,281; 4,690,981; 4,984,803; 4,979,746; 4,955,966; 4,931,376; 4,919,434; 4,911,451;.4,884,814; 4,863,167; 4,848,770; 4,792,141; 4,715,607; 4,714,253; 4,688,801; 4,683,257; 4,625,964; 4,483,537; 4,436,276; 4,431,193; 4,266,772; 4,065,537; 3,704,209; 3,572,722; 3,264,272.
In order to alleviate the problem of having to deal with balls which may have been immersed and recovered, in the subject invention a golf ball is provided which changes color, has imprinted writing which disappears or has some other indicia which changes after immersion to indicate that the ball has been immersed.
In the present invention, in one embodiment, imprints on the ball are made with water-activated ink which vanishes when it is exposed to water for long periods of time. In another embodiment, imprints on the ball are made with water-activated transparent ink which appears when it is exposed to water for long periods of time. The invention is thus used as an indicator of balls previously exposed to water to for one to several days in the bottom of a lake, pond, pool or other body of water. Such an indicator is used to alert golfers to potential changes in ball properties due to long water exposure times.